An early analysis of the existing observational data
presented in [1]} concluded that most of the QM
EOSs were too soft and therefore unable to support the existence of
neutron stars with a quark phase. Since then it was shown in several
works that a self-bound star, composed entirely of quark matter, could
explain a massive neutron star. In order to obtain a stiff enough quark matter
equation of state, several groups introduced repulsive interactions among
the quarks, mediated by the exchange of vector particles
[2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, which can be
“effective massive gluons” or “effective vector mesons”. Interestingly,
most of these developments make use of a mean field approximation for the
vector field and arrive at a similar result, which is a
quadratic term in the baryon density present both in the pressure and energy density.
